A related art stapler has a driver mechanism configured to drive a staple through sheets of paper, and a clincher mechanism configured to bend leg portions of the staple penetrating through the paper sheets to bind the paper sheets (see, e.g., JP2003-311646A, JP2003-311647A and JP2004-230482A). The clincher mechanism includes, for example, a clincher configured to engage with the leg portions of the staple to bend the leg portions, and a clincher guide having a guide portion configured to guide the clincher. The clincher is provided in the base so as to be movable relative to the base in a direction towards and away from the driver mechanism. The guide portion guides the clincher when the clincher is moving. The clincher is configured to allow, when bending the leg portions of the staple, a certain degree of deviation from the position at which the staple is stuck by the driver mechanism. A gap between the guide portion and the clincher is reduced to be minimum limit so as to prevent foreign objects, such as dust, from entering inside the clincher mechanism.
However, when for example a staple is struck by the driver mechanism in a state in which the staple is not held in a regular position due to jamming or the like, or when binding hard papers or more than a prescribed number of sheets of paper, the leg portions of the staple may deviate beyond the allowable range, in which case the leg portions fail to hit the clincher and enter the gap between the clincher and the guide portion such that the leg portions are stuck in the gap. In such a case, not only that it results in a stapling failure, but also it is difficult to remove the staple from the clincher mechanism. For example, in a case in which the driver mechanism is an electrical type, due to a large driving power, the staple is tightly caught in the gap. As a consequence, an attempt to pull out the paper sheets merely results in tearing the paper sheets, and the staple remains in the clincher mechanism. In particular, when the electric stapler is installed in an apparatus, such as copiers and printers, it is not easy to access a binding entrance from which the paper sheets are inserted between the driver mechanism and the clincher mechanism. Thus, it is extremely onerous to remove the staple from the clincher mechanism.